All-optical wavelength-bypassing ring communications networks

We introduce an all-optical WDM packet communication network that performs wavelength bypassing at the routers. Packets that arrive at a wavelength (o ptical cross-connect) router at designated wavelengths are switched by the router without having their headers examined. Thus, the processing element of the router is bypassed by such packets. For packet traffic that uses wav elengths that do not bypass a switch, the headers of such packets are exami ned to determine if this switch is the destination for the flow. If latter is the case, the packet is removed. Otherwise, the packet is switched to a pre-determined output without incurring (network internal) queueing delays. We study a ring network with routers that employ such a WDM bypassing sche me. We present methods to construct wavelength graphs that define the bypas sing pattern employed by the routers to guide the traffic flows distributed at each given wavelength. Performance is measured in terms of the network throughput and the average processing path length (i.e., the average number of switches not being bypassed). For a fixed total processing capacity, we show that a WDM bypassing ring network provides a higher throughput level than that exhibited by a non-bypassing ring network, using the same value o f total link capacity. By using WDM bypassing, the average processing path length (and thus the packet latency) is reduced. We study a multitude of ne twork loading configurations, corresponding to distinct traffic matrices an d client-server scenarios. Higher throughput levels are obtained for networ k configurations driven by non-uniform traffic matrices. The demonstrated a dvantages of WDM bypassing methods shown here for WDM ring networks are als o applicable to more general network topological layouts.